<?php

/**
 * @ingroup database
 * @{
 */

/**
 * @file
 * Query code for PostgreSQL embedded database engine.
 */


class InsertQuery_pgsql extends InsertQuery {

	public function execute() {
		if (!$this->preExecute()) {
			return NULL;
		}

		$stmt = $this->connection->prepareQuery((string) $this);

		// Fetch the list of blobs and sequences used on that table.
		$table_information = $this->connection->schema()->queryTableInformation($this->table);

		$max_placeholder = 0;
		$blobs = array();
		$blob_count = 0;
		foreach ($this->insertValues as $insert_values) {
			foreach ($this->insertFields as $idx => $field) {
				if (isset($table_information->blob_fields[$field])) {
					$blobs[$blob_count] = fopen('php://memory', 'a');
					fwrite($blobs[$blob_count], $insert_values[$idx]);
					rewind($blobs[$blob_count]);

					$stmt->bindParam(':db_insert_placeholder_' . $max_placeholder++, $blobs[$blob_count], PDO::PARAM_LOB);

					// Pre-increment is faster in PHP than increment.
					++$blob_count;
				}
				else {
					$stmt->bindParam(':db_insert_placeholder_' . $max_placeholder++, $insert_values[$idx]);
				}
			}
			// Check if values for a serial field has been passed.
			if (!empty($table_information->serial_fields)) {
				foreach ($table_information->serial_fields as $index => $serial_field) {
					$serial_key = array_search($serial_field, $this->insertFields);
					if ($serial_key !== FALSE) {
						$serial_value = $insert_values[$serial_key];

						// Force $last_insert_id to the specified value. This is only done
						// if $index is 0.
						if ($index == 0) {
							$last_insert_id = $serial_value;
						}
						// Set the sequence to the bigger value of either the passed
						// value or the max value of the column. It can happen that another
						// thread calls nextval() which could lead to a serial number being
						// used twice. However, trying to insert a value into a serial
						// column should only be done in very rare cases and is not thread
						// safe by definition.
						$this->connection->query("SELECT setval('" . $table_information->sequences[$index] . "', GREATEST(MAX(" . $serial_field . "), :serial_value)) FROM {" . $this->table . "}", array(':serial_value' => (int)$serial_value));
					}
				}
			}
		}
		if (!empty($this->fromQuery)) {
			// bindParam stores only a reference to the variable that is followed when
			// the statement is executed. We pass $arguments[$key] instead of $value
			// because the second argument to bindParam is passed by reference and
			// the foreach statement assigns the element to the existing reference.
			$arguments = $this->fromQuery->getArguments();
			foreach ($arguments as $key => $value) {
				$stmt->bindParam($key, $arguments[$key]);
			}
		}

		// PostgreSQL requires the table name to be specified explicitly
		// when requesting the last insert ID, so we pass that in via
		// the options array.
		$options = $this->queryOptions;

		if (!empty($table_information->sequences)) {
			$options['sequence_name'] = $table_information->sequences[0];
		}
		// If there are no sequences then we can't get a last insert id.
		elseif ($options['return'] == Database::RETURN_INSERT_ID) {
			$options['return'] = Database::RETURN_NULL;
		}
		// Only use the returned last_insert_id if it is not already set.
		if (!empty($last_insert_id)) {
			$this->connection->query($stmt, array(), $options);
		}
		else {
			$last_insert_id = $this->connection->query($stmt, array(), $options);
		}

		// Re-initialize the values array so that we can re-use this query.
		$this->insertValues = array();

		return $last_insert_id;
	}

	public function __toString() {
		// Create a sanitized comment string to prepend to the query.
		$comments = $this->connection->makeComment($this->comments);

		// Default fields are always placed first for consistency.
		$insert_fields = array_merge($this->defaultFields, $this->insertFields);

		// If we're selecting from a SelectQuery, finish building the query and
		// pass it back, as any remaining options are irrelevant.
		if (!empty($this->fromQuery)) {
			return $comments . 'INSERT INTO {' . $this->table . '} (' . implode(', ', $insert_fields) . ') ' . $this->fromQuery;
		}

		$query = $comments . 'INSERT INTO {' . $this->table . '} (' . implode(', ', $insert_fields) . ') VALUES ';

		$max_placeholder = 0;
		$values = array();
		if (count($this->insertValues)) {
			foreach ($this->insertValues as $insert_values) {
				$placeholders = array();

				// Default fields aren't really placeholders, but this is the most convenient
				// way to handle them.
				$placeholders = array_pad($placeholders, count($this->defaultFields), 'default');

				$new_placeholder = $max_placeholder + count($insert_values);
				for ($i = $max_placeholder; $i < $new_placeholder; ++$i) {
					$placeholders[] = ':db_insert_placeholder_' . $i;
				}
				$max_placeholder = $new_placeholder;
				$values[] = '(' . implode(', ', $placeholders) . ')';
			}
		}
		else {
			// If there are no values, then this is a default-only query. We still need to handle that.
			$placeholders = array_fill(0, count($this->defaultFields), 'default');
			$values[] = '(' . implode(', ', $placeholders) . ')';
		}

		$query .= implode(', ', $values);

		return $query;
	}
}

class UpdateQuery_pgsql extends UpdateQuery {
	public function execute() {
		$max_placeholder = 0;
		$blobs = array();
		$blob_count = 0;

		// Because we filter $fields the same way here and in __toString(), the
		// placeholders will all match up properly.
		$stmt = $this->connection->prepareQuery((string) $this);

		// Fetch the list of blobs and sequences used on that table.
		$table_information = $this->connection->schema()->queryTableInformation($this->table);

		// Expressions take priority over literal fields, so we process those first
		// and remove any literal fields that conflict.
		$fields = $this->fields;
		$expression_fields = array();
		foreach ($this->expressionFields as $field => $data) {
			if (!empty($data['arguments'])) {
				foreach ($data['arguments'] as $placeholder => $argument) {
					// We assume that an expression will never happen on a BLOB field,
					// which is a fairly safe assumption to make since in most cases
					// it would be an invalid query anyway.
					$stmt->bindParam($placeholder, $data['arguments'][$placeholder]);
				}
			}
			unset($fields[$field]);
		}

		foreach ($fields as $field => $value) {
			$placeholder = ':db_update_placeholder_' . ($max_placeholder++);

			if (isset($table_information->blob_fields[$field])) {
				$blobs[$blob_count] = fopen('php://memory', 'a');
				fwrite($blobs[$blob_count], $value);
				rewind($blobs[$blob_count]);
				$stmt->bindParam($placeholder, $blobs[$blob_count], PDO::PARAM_LOB);
				++$blob_count;
			}
			else {
				$stmt->bindParam($placeholder, $fields[$field]);
			}
		}

		if (count($this->condition)) {
			$this->condition->compile($this->connection, $this);

			$arguments = $this->condition->arguments();
			foreach ($arguments as $placeholder => $value) {
				$stmt->bindParam($placeholder, $arguments[$placeholder]);
			}
		}

		$options = $this->queryOptions;
		$options['already_prepared'] = TRUE;
		$this->connection->query($stmt, $options);

		return $stmt->rowCount();
	}
}
